Question

Avoiding repeated records in table

I have a Table like one below

CREATE TABLE models(model_id INT NOT NULL PRIMARY KEY AUTO_INCREMENT,
                         model_no varchar(255));                             

INSERT INTO models(model_no)
                 VALUES('M24'),
                       ('M22'),
                       ('M25'),
                       ('M24'),
                       ('M24'),              
                       ('M35'),
                       ('M15'),
                       ('M18'),
                       ('M25'),
                       ('M15'),
                       ('M15'),
                       ('M17'),
                       ('M19'),
                       ('M29'),
                       ('M29'),
                       ('M12'),
                       ('M12'),
                       ('M13'),
                       ('M29');

I want to remove the repeated model from this table by running a delete or update query so that the model will occur only once as below

1    M24
2    M22
3    M25
6    M35
7    M15
8    M18
12   M17
13   M19
14   M29
16   M12
18   M13

Answer 1

delete m from models m
join models m2 on m2.model_no = m.model_no and m.model_id > m2.model_id